To play the actual God of War Ragnarök, you must use one of the officially supported platforms: God of War Ragnarök on Steam

These titles were built specifically for the PSP and provide the best portable experience through emulation. How to Play the Real God of War Ragnarök

God of War Ragnarök is a modern triple-A title requiring massive storage (nearly 190 GB on PC) and advanced graphical power that far exceeds the capabilities of the PlayStation Portable (PSP) hardware.